<template>
  <view>
    <!-- 搜索模块 -->
    <search></search>
    <!-- 主体区域 -->
    <view class="m-category">
      <scroll-view scroll-y class="left">
        <view 
        class="item"
        :class="{active:activeIndex===index}"
        @click="changeActive(index)"
         v-for="(item,index) in lifeList" 
         :key="item.cat_id">{{ item.cat_name }}</view>
      </scroll-view>
      
      <scroll-view :scroll-top="scrollTop" scroll-y class="right">
        <view class="cate" v-for="item in rightList" :key="item.cat_id">
          <view class="title">{{ item.cat_name }}</view>
          <view class="goods-list">
            <navigator :url="`/goodsPkg/goods_list/goods_list?query=${goods.cat_name}&cid=${goods.cat_id}`" class="goods" v-for="goods in item.children" :key="goods.cat_id">
              <image
                :src="goods.cat_icon"
                class="pic"
                mode="aspectFit"/>
              <view class="name">{{ goods.cat_name }}</view>
            </navigator>
          </view>
        </view>
      </scroll-view>
    </view>
  </view>
</template>

<script>
export default {
  name:'Category',
  data(){
    return{
   lifeList:[],
   cateList:[],
   rightList:[],
   activeIndex:0,
   scrollTop:0
    }
  },
  onLoad(){
    this.getCateList()
  },
  methods:{
    async getCateList(){
      const {message}= await uni.$u.http.get('/categories')
      this.cateList=message
      // 性能优化，大数组变小数组
      this.lifeList=message.map(item=>({cat_name:item.cat_name,cat_id:item.cat_id}))
      // 获取数据后再点击
      // 默认0点击
      this.changeActive(0)
    },
    changeActive(index){
      this.activeIndex=index
      // console.log(this.cateList[index].children);
      this.rightList = this.cateList[index].children

      // 先将scrollTop=-1，监听数据的变化
      this.scrollTop=-1
      // 滚动到顶部
      this.$nextTick(()=>{
        this.scrollTop=0
      })
    }
  }
};
</script>

<style lang="scss">
.m-category {
  display: flex;
  height: calc(100vh - 20rpx - 34px);
  .left {
    height: 100%;
    width: 182rpx;
    font-size: 28rpx;
    text-align: center;
    background-color: #F3F3F3;
    .item {
      padding: 17rpx 0;
      &.active{
        background: #fff;
        color: #ea4350;
        position: relative;
        &::before{
          content: '';
          position: absolute;
          left: 0;
          width: 4rpx;
          height: 44rpx;
          background: #ea4350;
        }
      }
    }
  }
  .right {
    height: 100%;
    flex: 1;
    .title{
      margin: 18rpx 0 21rpx;
      text-align: center;
    }
  }
}
.goods-list{
  display: flex;
  padding: 0 48rpx;
  justify-content: space-between;
  flex-wrap: wrap;
  .pic{
    width: 120rpx;
    height: 120rpx;
  }
  .name{
    margin-bottom: 30rpx;
    font-size: 21rpx;
    color: #2E2E2E;
    text-align: center;
    line-height: 1;
  }
}
</style>